The present work focused on examining the function of rumen-protected L-arginine (RP-Arg) or N-carbamylglutamate (NCG) in jejunal oxidative resistance, integrity and immune function in the ovine foetal model of intrauterine growth restriction (IUGR). Thirty-two twin-bearing Hu ewes at d 35 of gestation were randomised as 4 treatment groups (n = 8 each): Control (CON), received 100% of the recommended National Research Council (NRC) for pregnancy; Restricted (RES), received 50% of the recommended NRC for pregnancy; RES + ARG, RES ewes added with 20 g/d of RP-Arg; or RES + NCG treatment, RES ewes added with 5 g/d of NCG. Foetal jejunal samples were collected on d 110 of pregnancy and were assayed for biomarkers of oxidative damage, integrity and immune function. The villus height was elevated (p